一下子
all at once; suddenly; in one go
Structure
一下子 （就）动词／形容词（了）
What it means
Stresses that a change happens fast or all at once, or that a large amount is done in one go.
How it is built
一下子 + (就) + verb/adjective + 了, often with verbs of change (变, 降, 涨, …起来): 气温一下子降了十度 (the temperature dropped ten degrees all at once).
When to use it
突然 is about surprise; 一下子 is about speed and scale (一下子买了五本书). In the negative it means “straight off, in one go”: 一下子说不清 (can’t explain it just like that).
Watch out
Don’t confuse it with verb + 一下, which softens a request: 看一下 (have a quick look). 一下子 goes before the verb and stresses speed or amount.
Examples
冷空气一来，气温一下子降了十度。
When the cold air arrived, the temperature dropped ten degrees all at once.
听说明天放假，教室里一下子热闹起来了。
At the news of a day off tomorrow, the classroom suddenly came alive.
这么多生词，我一下子记不住。
So many new words: I cannot remember them all in one go.
Learn this in Lesson 15 · HSK 5: 梅雨、回南天与台风 (Plum rains, “returning south” days and typhoons)
A dialogue, a reading, word cards with audio and a drill that uses it, in Learn Chinese with Bao. The first lessons of every level are free.
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